Protective relay / relay protection

A protective relay is a device that continuously monitors electrical conditions (like current and voltage) and automatically triggers a circuit breaker to disconnect equipment when it detects a dangerous condition, such as a short circuit. This automated protection is what limits the damage and disruption from an electrical fault before it can cascade further.

NERC does not define "protective relay" as its own standalone term; it appears as one component within NERC’s formal "Protection System" definition.